Moistureproof article



Patented Nov. 9, 1937 UNITED. STATES PATIENT OFFICE amsu MOISTUREPB/OOF ARTICLE William Hale Charch, Builalo, N. Y., and Merlin Martin Brubaker and Frederick M. Neill, Wilmington, Del., assignora, by memo assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del a corporation of Dela- No Drawing. Application December :1, 1934, Serial No. 158.652

9 Claims.

This invention relates to the art of moistureproofing. More particularly, it relates to a composition oi matter suitable for the production of moistureproof materials and also to the moistureproof materials per se.

We believe that moistureproofing is due to (1) the use of an agent which is inherently moistureproof, and (2) the laying down of this agent in a continuous unbroken him, either alone or in combination with other materials or vehicles hereinafter called film-forming substances.

We have found, as a result of a large number of experiments, that substances are inherently moistureproof when they are of such a nature that they are not only insoluble in water but also dissolve none or at least only an infinitesimal amount of water. Apparently, water vapor diffuses through continuous unbroken films of such substances'by a process of dissolving in the film and evaporating from-the other side. The solubility of water in the moistureproofing agent largely determines the rate of transfusion of water vapor through the film, and therefore its inherent moistureproofness. Obviously, if the film is noncontinuous and broken, other factors enter into the determination of the degree of moistureproofness.

We have found that organic alcohols of the type hereafter more fully described can be used in the preparation of moistureproofing compositions which will yield moistureproof films, i. e. coatings or self-sustaining films which are preferably also transparent, glossy, non-tacky, flexible, possess good surface slip, etc.

For the purposes of this specification and claims, we define moistureproof materials as those which, in the form of continuous unbroken sheets or films, permit the passage of not more than 570 grams of, water vapor per 100 square meters per hour, over a period of 24 hours, at approximately C.:0.2 C., the relative humidity of the atmosphere at one side of the film being maintained at least at 98% and the relative humidity of the atmosphere at the other side/being maintained at such a value as to give a humidity difierential of at least 95%.

Moistureproofing coating compositions are defined as those which, when laid down in the form of a thin, continuous, unbroken film applied uniformly as a coating with a total coating thickness not exceeding 0.0005" to both sides of a sheet of regenerated cellulose of thickness approximately 0.0009", will produce a coated. product which is moistureproof.

For the purpose of experimental tests, especially for those materials adaptable as coating com: positions, moistureproof materials include those substances, compounds or compositions which, when laid down in the form of a continuous unbroken film applied uniformly as a coating with a total coating thickness not exceeding 0.0005" to both sides of a sheet of regenerated cellulose of thickness approximately 0.0009", will produce .a. coated sheet which will permit the passage therethrough of not more .than 570 grams of water vapor per 100 square meters per hour over a period of approximately 24 hours, at a temperature of 35 C.:0.2 (2., with a water vapor pressure differential of 40-44 mm. (preferably 41.8:037 mm.) of mercury. For convenience, the number of grams of water vapor passed under these conditions may be referred to as "the permeability value. An uncoated sheet of regenerated cellulose having a thickness oi approximately 0.0009" will show a permeability value of the order of 5700.

From the foregoing, it is apparent that under the conditions set forth, a moistureproofed regenerated cellulose sheet is capable of resisting the passage of moisture or water vapor therethrough at least 10 times as effectively as the uncoated regenerated cellulose sheet.

We have specifically defined herein moistureproofness in terms of a permeability test performed at substantially 35 C. It is to be understood, however, that by the adoption of this condition no disclaimer is made of moistureproofness of any of the materials or compositions when tested'attemperatures lower than 35 C. Likewise, no disclaimer is made of moistureproofing effects exhibited by the materials herein described at temperatures above 35 C. There will be a temperature for each moistureproofing agent above which neither it nor compositions containing it show substantial resistance to the passage of moisture. However, this behavior does not disqualify the materials herein described as moistureproofing agents.

The critical temperature above which these Purposes it may be definitely advisable to use agents of lower melting points.

It is, therefore, an object of this invention to provide a composition of matter suitable for easting or coating purposes comprising a film-forming substance and an organicalcohol, more fully described hereafter, which will deposit a moistureproof film, i. e. a self-sustaining film or coating,

which is preferably also transparent, flexible, non-tacky, glossy and possesses good surface slip.

Another object of this invention is to provide moistureproof films, i. e. self-sustaining films or coatings containing organic alcohols which impart moistureproofness thereto, said filmsbeing also preferably transparent, flexible, non-tacky, glossy and possessing good surface slip.

Other objects will become apparent from'the following description and appended claims.

The instant invention, in one phase thereof, contemplates a fiowable composition of matter which will deposit a moistureproof film, i. e. a selfsustaining film or coating which, in the preferred embodiment, is transparent (glass-clear) flexible, glossy, non-tacky and possesses good surface slip. The composition consists of an agent which affords the basis for molstureproofness, and a filmforming substance. In the preferred embodiment, the composition also includes a solvent or solvent mixture, a plasticizer and/or a blending agent.

As the agents which afford the basis for the moistureproofness, the instant invention contemplates solid organic alcohols which are inherently moistureproof and have a melting P int of at least 37 C. The molecule of the moistureproof alcohols is largely hydrocarbon carbon, but may contain the usual modifying groups, such as carbonyl, halogen, ester, etc., providing it has a sufllciently high hydrocarbon carbon content to offset the afilnity for water for these substituent groups. In so far as this specification is concerned, a hydrocarbon carbon atom is one which has at least three of its valences attached to carbon or hydrogen.

When a monohydric organic alcohol containing no modifying group in the molecule is used as a moistureproofing agent, we have found that the molecule must contain at least 20 hydrocarbon carbon atoms in the hydrocarbon portion thereof for the hydroxyl group in order to achieve a moistureproofing effect. When more than 20 hydrocarbon carbon atoms are present, better moistureproofing effects are secured. As to the hydrocarbon carbon atoms in the hydrocarbon portion of the molecules, 12 or 15 of the hydrocarbon carbon atoms are aliphatic in nature.

It is to be understood that this invention contemplates the use of monoor polyhydric, primary, secondary or tertiary alcohols, and which may or may not contain additional active or modifying groups. Any group or atom other than hydrocarbon is considered an active group. We have found that, when the number of active groups is increased, the limiting ratio of hydrocarbon carbon atoms to the active group is decreased. For example, when two similar active groups are present, the limiting ratio may be 55 -66% of the limiting ratio for one such group, while for three similar active groups the limiting ratio is 45%-55% and approaches a limiting value of 30% as the number of similar active groups is further increased. When different active groups are introduced, the limiting ratio of hydrocarbon carbon atoms will vary, depending upon the nature and number of such groups.

cohols which are moistureproof and can be .utilized in the preparation of moistureproof films.

As previously mentioned, the composition also contains a film-forming substance. As illustrative examples-of film-forming substances may be mentioned cellulose derivatives, for example, cellulose nitrate, cellulose acetate, ethyl cellulose, benzyl cellulose, mixed esters or other esters; resins, either natural or synthetic, such as rosin, hydrogenated rosin and its derivatives, including glycerol, glycol or diethylene glycol esters of hydrogenated rosin; rosin esters of glycerol, glycol or diethylene glycol; gum dammar; polybasic acid-polyhydric alcohol resins, either modified or unmodified; vinyl resins of the polymerized vinyl acetate, polymerized chlor-vinyl acetate and polymerized vinyl acetal resin types; metastyrene resin; phenolic condensation products; rubber, gutta percha, balata, caoutchouc; synthetic rubbers including polymers of isoprene, butadiene and their homologues; chemical derivatives of rubber, such as halogenated rubber, rubber treated with sulphuric acid, rubber treated with tin tetrachloride, rubber treated with chlorostannic acid; varnishes; etc. One or a plurality of film-forming ingredients may be used. The precise filmforming ingredient or mixture thereof depends upon the purpose for which the compositions are to be used.

when the composition contains a softener, any suitable softener for the film-forming ingredient may be used. For example, diamyl phthalate, tricresyl phosphate, dicyclohexyl phthalate, butyl benzoyl benzoate, etc. may be used, when the filmforming ingredient is a cellulose derivative.

' In some compositions wherein a cellulose derivative is used, the film which is produced may be hazy. If desired, this may be overcome by incorporating in such a composition a blending agent. Such compositions also are generally more moistureproof than those without the blending agent or gum. The blending agent tends to improve the compatibility of the moistureproofing agents with the other ingredients in the film and consequently the impermeability of the film. As several illustrative examples of blending agents may be mentioned gums or resins, such as dammar, gum elemi, ester gum, hydrogenated rosin; hydrogenated ester gum or the like, halogenated diphenyl, a natural occurring balsam or a synthetic balsam-like substance, such asdiethylene glycol hydrorosinate, or a substance such as lanum, hydrogenated castor oil, di-dodecyl phthalate, retene, diricinoleic ester of glycerol or the like.

The ingredients which constitute the final film may be dissolved in an appropriate solvent or solvent mixture to form a solution which may be used as herein described. Alternatively, the ingredients constituting the final film may be used in the form of a melt. When the composition is to be used in the form of a melt, it is desirable to include therein a blending agent to inhibit crystallization. Hydrogenated rubber, hydrogenated ester gum, rosin, dammar, diethylene glycol hydrorosinate and the like, are several illustrative examples of crystallization inhibitors. Whenever aooasss the composition is in the form of a lacquer and used for coating purposes. the solvents thereof are chosen so that theywill not produce any deleterious eiiects on the base being coated The proper formulation of the lacquer so that it will yield coatings which are transparent and highly moistureproof is determined by tests. One of the most important things to be determined is the proper amount of blending agent to be used.-

This can be determined, for example. as follows: A series of compositions is prepared containing the same amounts of lacquer base, softener, moistureproofing agent and solvent. Different quantities of blending agent are then added to each of these lacquers and the general properties, such as transparency and the permeability values of sheets of regenerated cellulose, for example. coated with each of these compositions, are plotted against the ratio of blending agent to moistureproofing agent used.

When a lacquer of the type described in Example VII is modified according to this systematic procedure. it will be found that the lowest permeability value occurs very near the point where the coatings become completely transparent. In the case of diheptadecyl carbinol in this particular composition, this point is equivalent to approximately 335 to 6 grams of dammar to 1 gram of diheptadecyl carbinol. It is obvious that this optimum blending agent-moistureproofing agent ratio will vary for different moistureproofing agents'and for different blending ents with the same moistureproofing agent. In general, this ratio depends upon the hydrocarbon carbon content and the solubility of the moistureproofing agent in the lacquer solids. Thus, the ratio is high for molstureproofing agents having high hydrocarbon carbon content and low for moistureproofing agents which are quite soluble or compatible with the other constituents of the coating. Undoubtedly, other factors, such as melting point, solvent composition of the lacquer, type of lacquer base used, choice of plasticizer, etc., also aifect this optimum ratio, but the two considerations mentioned above seem to be the more important ones.

A series of experiments, based on the composition of Example VII will, of course. have a pyroxylin lacquer base and a pyroxylin-moistureprooflng agent ratio of 5.26:1. Obviously, this ratio can also be varied and the relations between permeability value and the blending agent-moistureproofing agent ratio determined for sheets of regenerated cellulose coated with a series of lacquers having a different lacquer base-moistureproofing agent ratio to which various amounts of dammar or other blending agent have been added. These relations will have the same general character but it will be found generally that, as the lacquer base-moistureprooiing agent ratio is increased (decreasing the quantity of moistureprooflng agent), the permeability values will be higher for a given blending agentmoistureprooilng agent ratio and will eventually agent ratio usually falls within the limits 1:10 to 200:1 and the blending agent-moistureproofing agent ratio lies between the limits of :1 to :1. The most satisfactory cellulose derivative basemoistureprooflng lacquers generally fall within these limits for nearly. all moistureprooflng agents,the optimum pyroxylin-moistureprooflng agent ratios being of the order of 2:1 to 30:1. However, for certain purposes, for example, compositions for casting moistureproof foil, the

ratios may diifer greatly from those given above and we donot intend that we should be confined to these limits which are suggested merely as an aid to the proper formulation of moistureprooiing lacquers.

The above or any other method fordetermining themost satisfactory formula in which to use any moistureproofing agent to achieve minimum permeability and maximum clarity of coating may be used. The above discussion is merely given as one systematic method, whereby compositions may be formulated with the moistureproofing agents here disclosed. Different moistureproofing agents will yield different data on such a series of experiments as this, and moistureproofing agents of different chemical constitution will be formulated differently into various dopes or vehicles. There is thus no single composition such as has been described above which is universal in its application. The specificexamples hereafter given are thus illustrative, and the above-described method of systematically varying the compositions of solids in which a moistureprooilng agent is used is exemplary of a general method, whereby optimum results may be achieved with an agent. The method is, of course, capable of extension to include variations of any of the solid lacquer in gradients, or even to include solvents and the solvent composition. Thus, when one skilled in the art is taught by these disclosures, he will be able to formulate a variety of compositions containing any of the moistureproofing agents or to determine those compositions with which our moistureprooflng agents are most advantageously used. A moistureproofing agent is thus not a material which will always and universally produce moistureproof coatings utterly regardless of the composition in which it is used. It usually requires to be formulated in certain favorable compositions to bring out its inherent moistureproofing properties. on the other hand, a substance which is not inherently moisturep'roof cannot by any extended amount of work in formulation be made to yield moistureproof films or coatings. Thus, when we speak of the inherent property of a compound to moistureproof, we are concerned with a specific inherent property which permits it to be used with some film-forming vehicle to produce moistureproof coatings.

The composition can be used for the production of films, either by casting it in the wellknown manner to produce self-sustaining films, or by coating it on to the selected base. When the composition is to ,be used as a coating, any suitable base material, paper, highly calendered paper, glassine, leather, fabrics, etc. may be-used. The compositions may even be applied to metals to prevent them from rust by virtue of their moistureproofing property. They may also be used to coat individual fibers of cotton, wool or artificial silk in such a manner as to make them moistureproof. In the preferred embodiment of the invention, when a transparent wrapping tissue is desired, the base may consist of thin, dense, non-fibrous, substantially non-porous and preferably transparent sheeting formed of a cellulosic, albuminous or other material. As illustrative examples of cellulosic sheeting may be mentioned cellulosic sheeting coagulated or precipitated from an aqueous dispersion or solution of a cellulosic material, for example, sheeting of regenerated cellulose, glycol cellulose, cellulose glycollic acid, lowly etherifled or esterifled cellulose, such as lowly methylated cellulose; and sheeting of cellulose derivatives, such as cellulose acetate, cellulose nitrate, ethyl cellulose, benzyl cellulose. Gelatin and casein, hardened or not as desired, are mentioned as illustrative examples of albuminous materials. Sheeting of rubber or rubber derivatives may also be used as the base.

When a selected base, as for example regenerated cellulose sheeting, is to be moistureproofed by the compositions hereinbefore described, the composition is applied to the regenerated cellulose sheeting in any suitable manner, such -as immersion, spraying brushing, etc. The lacquer may be, if necessary, maintained at the time of application at an elevated temperature in order to prevent separation of the moistureprooflng ingredients. The excess composition is removed by any suitable means and substantially all the volatile solvents are removed from the composition at an elevated temperature, for example, C.-l10 C., in order to prevent separation or crystallization of the moistureprooflng agent during evaporation of the solvent. It is also preferable to use air low in moisture content during the drying operation in order to obtain evaporation of the solvent without illm blush. After being dried, the product, if the base is of the type which loses moisture at elevated temper-- (A) A composition consisting of the following ingredients in approximately the proportions set forth is prepared in any convenient and appropriate manner:

Parts by weight Pyroxylin 5.26 Gum dammar 3.25 Dibutyl phthalate 2.32 Diheptadecyl carbinol 1.00 Ethyl acetate 46.25 Toluene 36.00 Alcohol 6.28 Acetone 0.68

'A transparent sheet of regenerated cellulose is submerged in this lacquer which, for convenience, is maintaine i at a temperature of 40 C. in order to prevent separation of the moistureprooflng agent. The excess lacquer is removed by suitable means and the coated sheet is dried,

preferably promptly, at an elevated temperature, and preferably also at 90 C.-1l0 C. The coated sheet is glass-clear in transparency, flexible, nontacky, glossy, possesses good surface slip and is only approximately 0.00005" to 0.00015" thicker than the uncoated sheet and it is practically impossible to distinguish the coated sheet from the uncoated sheet in appearance. However, the coated sheet is moistureproof, having a permeability value of less than 570, for example, of the order of or even less. It is apparent that these permeability values indicate 10 to 50 fold improvement over an uncoated sheet of regenerated cellulose as regards resistance to the passage of moisture or water vapor.

The coated sheet is much more resistant to the e of water vapor than a similar sheet coated with the same lacquer except for the omission of diheptadecyl carbinol or a sheet coated, for example, with a high grade waterproof spar varnish. A sheet coated with the lacquer without the addition of diheptadecyl carbinol will have a permeability value of 4,000 to 5,000, while the sheet coated with a waterproof spar varnish will have a permeability value of from 2,000 to 4,000.

(B) Diheptadecyl carbinoi in Example I(A) above is substituted by an equal amount of montanyl alcohol. The process of Example I(A) is utilized to coat regenerated cellulose sheeting. The product H w the same characteristics as the product of Example I(A) except that the product produced by the instant example has a permeability value of less than 570, for example, of the order of 200 or less.

(C) In Example I(A) substitute diheptadecyl carbinol by an equal amount of ceryl alcohol. The process of Example I(A) is used to coat transparent regenerated cellulose sheeting. The product possesses the same properties and characteristics as that of Example I(A) except that the product produced by the instant example has a permeability value of less than 570, for example, of the order of 240 or even less.

Example 11 A composition consisting oi. the following ingredients in approximately the proportions set forth is prepared by any well-known procedure:

Transparent sheets of regenerated cellulose are coated and treated in the manner described in Example I(A) The product is transparent, flexible, glossy, has good surface slip and a permeability value of 570 or less.

Example III A composition consisting of the following ingredients in approximately the proportions set forth is prepared by any well-known procedure:

Parts by weight Ethyl cellulose 6.0 Rosin 3.6 Tricresyl phosphate 1.0 Cery] alcohol 1 Toluene 60.0 Alnnhgl 19.0 Ethyl lactate 10.0

Transparent sheets of regenerated cellulose are coated and treated in the manner described in- Example I(A). The product is transparent, flexibie, glossy, has good surface slip and will have a permeability value of 570 orless.

Further, compositions of this type may be used for protecting steel and other corrodible metals against rust and the like. These coatings may be air-dried at room temperature for 1 hour and are at least 10 to 75 times as impermeable to moisture vapor as similar coatings containing no moistureprooiing agents.

The omission of ethyl lactate will provide a composition suitable for coating sheets of cellulose acetate and such coated sheets will have a permeability value of 570 or less. This product is also transparent, flexible, glossy and possesses good surface slip.

As previously explained, in many cases it may be desirable to omit the gum or resin entirely, though when used it may materially improve the transparency of the final product.

The following are. examples of moistureproofing compositions containing no gum or resin:

Example IV A composition consisting of the following ingredients in approximately the proportions set forth is prepared in any well-known manner:

Parts by weight Pyroxylin 5.26 Dibutyl phthalate 2.32 Montanyl alc 1.00 Ethyl acetate 46.25 Toluene 36.00 Alcohol i 6.28 Acetone 0.68

Regenerated cellulose sheets thinly coated with this lacquer and dried at room temperature will have a permeability value of the order of 570 or less. 4

Example V I A composition consisting of the following ingredients in approximately the proportions set forth is prepared in any well-known manner:

. Parts by weight Pyroxylin 5.26 Dibutyl'phthalate 2.32 Ceryl alcohol 1.00 Ethyl acetate 46.25 Toluene 36.00 Alcohol--- 6.28 Acetone 0.68

A highly calendered smooth paper is provided with a continuous layer of this lacquer by coating with or without impregnation and then drying at 90 C.l10 C. The product has a permeability valueof the order of 150 or less.

Example VI A composition consisting of the following ingredients in approximately the proportions set forth is prepared in any well-known manner:

Regenerated cellulose sheeting is coated with this composition and dried as set forth in Example HA). The product has a permeability value of the order of 425 or less.

Example VII A composition consisting of the following ingradients in approximately the proportions set forth is prepared in any well-known manner:

Regenerated cellulose sheeting coated as explained in Example I(A) and force-dried at C.-- C. produces a coated product having a permeability factor of the order of 400 or less.

The compositions described in Examples IV to VII inclusive may yield coatings which are slightly hazy. If transparency is essential, a. blending agent of the type previously mentioned may be incorporated in these compositions. Thus, for example, the lacquer described in Example VII may be so modified that it will always yield transparent coatings by the addition of a blending agent, such as dammar. The quantity of dammar or other blending agent to be added must be determined as previously described.

The following is an example of a composition wherein a polybasic acid-polyhydric alcohol resin constitutes the film-forming ingredient. This composition consisting of the. following ingredients in approximately theproportions given is prepared in any suitable manner:

Parts by weight Perilla oil-polybasic acid-polyhydric alcohol resin varnish 50 Ceryl alcohol 1 Toluene 50 The perilla oil-polybasic acid-polyhydric alcohol resin varnish is prepared from the following ingredients:

The procedure for preparing the perilla oilpolybasic acid-polyhydric alcohol resin varnish is as follows: Heat 72.6 parts of C. P. glycerin to 350 F. in closed kettle-condenser and stirrer. At 350 F. add NaOH, followed by perilla oil. Stir rapidly and heat to 437 F. Hold until clear (15- 30 minutes). Add phthalic anhydride and heat to'392" F. Add residue of glycerin to batch. Heat to 392 F. and hold (5 hours). Acid number 45- 55. Cool to F. Cut with ethyl acetate. Add drier and centrifuge. (Solids 50%.)

Regenerated cellulose sheeting coated with this composition, as explained under Example I(A), and dried at room temperature, or at 90 C.-110 0., produces a product having a permeability value of the order of 200 or less. A composition 'of this type may be used without blending agents,

but in some cases'it is advantageous to use a small amount of gum. Usually compositions of this nature are sumciently flexible without the addition of a plasticizer. Lacquers of this type compositions given in Examples I to VII inclusive may be used for this purpose. It is usually desirable, however, to employ a higher solids base solution for casting sheets than is ordinarily used for forming thin coatings. Furthermore, in view of the greater thickness of cast foils as compared to coatings, a smaller proportion of the moistureproofing agent is used in order to obtain transparency and a. high degree of moistureproofness, and this in turn will require the use of a smaller quantity of blending agent and/or the use of blending agents other than hard gums in appreciable quantities. Those skilled in the art will be able to formulate by tests satisfactory compositions for the preparation of cast sheets.

The cast sheets and protective coatings prepared in accordance with the instant invention have the ability to resist the tron or diffusion of water vapor to an extent at least 4 times that displayed by sheets of equal thickness and produced from similar or prior art compositions formulated without the addition of moistureproofing agents. The value 4" merely sets forth the minimum improvement and does not limit the higher moistureproofness that can be obtained. The moistureproofing agents herein described are capable of being formulated into films showing improvement over prior art films produced from compositions formulated without the addition of moistureproofing agents not only 4 but 10, 20, 40 and in some cases even 100 fold. This is truly a remarkable accomplishment.

The compounds described in this application as moistureproofing agents have many advantages. Moistureproofing compositions containing the moistureproofing agents are easily duplicated. As previously stated, these compositions in certain formulations thereof yield coatings which air-dry at ordinary temperatures. For certain purposes where it is not feasible to force-dry the coatings, this becomes especially important. As for the moistureproofing agents. themselves, they are generally colorless, odorless, tasteless, nonvolatile, and essentially non-toxic. at least in the quantities in which they are used, and they can be reproduced synthetically with a high degree of uniformity and consistency.

In the definition hereinbefore set forth, it is to be understood that the permeability value of 570 represents only the maximum value. In many cases permeabilities of 235, 140, 57, 30 or indeed less may be obtained.

When bases of the preferred type are utilized, the ultimate product is admirably suited for use as a transparent moistureproof wrapping tissue.

Since it is obvious that various changes and modifications may be made in the above description without departing from the nature or spirit thereof, this invention is not restricted thereto except as set forth in the appended claims.

We claim:

1. An article of manufacture having a continuous unbroken moistureproof surface comprising a film-forming substance and a solid alcohol having a melting point of at least 37 C. as the moistureproofing agent, said alcohol being selected from the group which consists of diheptadecyl carbinol and methyl phenyl octadecyl carbinol and present in an amount to impart moistureproofness to said article.

2. An article of manufacture comprising a continuous unbroken moistureproof film comprising a film-forming substance and a solid alcohol having a melting point of at least 37 C. as the moistureproofing agent, said alcohol being selected from the group which consists of diheptadecyl carbinol and methyl phenyl octadecyl carbinol and present in an amount to impart moistureproofness to said article.

3. An article of manufacture comprising a continuous unbroken moistureproof film comprising a film-forming substance, a solid alcohol having a melting point of at least 37 C. as the moistureproofing agent, and a blending agent, the ratio of the quantity of film-forming substance to the quantity of alcohol being within the limits of 1:10 to 200:1 and the ratio of the blending agent to the quantity of alcohol being within the limits of :1 to :1, said alcohol being selected from the group which consists of diheptadecyl carbinol and methyl phenyl octadecyl carbinol and present in an amount to impart moistureproofness to said article.

4. An article of manufacture comprising a continuous unbroken moistureproof film comprising pyroxylin, a solid alcohol having a melting point of at least 37 C. as the moistureproofing agent, and a blending agent, the ratio of the quantity of pyroxylin to the quantity of alcohol being within the limits of 2:1 to 30: 1, said alcohol being selected from the class which consists of diheptadecyl carbinol and methyl phenyl octadecyl carbinol and present in an amount to impart moistureproofness to said article.

5. An article of manufacture comprising a transparent base sheet or film having a continuous transparent moistureproof coating. comprising a film-forming substance and a solid alcohol having a melting point of at least 37 C. as the moistureproofing agent, said alcohol being selected from the group which consists of diheptadecyl carbinol and methyl phenyl octadecyl carbinol and present in an amount to impart mois-' tureproofness to said article.

6. An article of manufacture comprising a transparent non-fibrous base sheet or film having a continuous transparent moistureproof coating comprising a film-forming substance and a solid alcohol having a melting point of at least 37 C. as the moistureproofing agent, said alcohol being selected from the group which consists of diheptadecyl carbinol and methyl phenyl octadecyl carbinol and present in an amount to impart moistureproofness to said article.

7. An article of manufacture comprising a transparent regenerated cellulose base sheet or film having a continuous transparent moistureproof coating comprising a film-forming substance and a solid alcohol having a melting point of at least 37 C. as the moistureproofing agent, said alcohol being selected from the group which consists of diheptadecyl carbinol and methyl phenyl octadecyl carbinol and present in an amount to impart moistureproofness to said article.

8. An article of manufacture comprising a transparent regenerated cellulose sheet or film having a continuous transparent moistureproof coating on each side thereof comprising a filmforming substance and diheptadecyl carbinol as the moistureproofing agent, the latter being present in an amount to impart moistureproofness to said article.

9. An article of manufacture comprising -a ter being present in an amount to impart moistransparent regenerated cellulose sheet or film having a continuous transparent moistureproof coating on each side thereof comprising a filmforming substance and methyl phenyi octadecyl carbinol as the moistureprooflng agent, the lattureproofness to said article.

WILLIAM HALE CHARCH. MERLIN MAR'ITN BRUBAKER. FREDERICK M. MEIGS. 

